﻿#region Copyright
// Copyright (c) 2011-2012 RaisingForce Team (Alikin Sergey)
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using System.Windows.Input;
using System.Diagnostics.Contracts;

namespace RaisingForce.Raise.Presentation
{
    /// <summary>
    /// A command whose sole purpose is to 
    /// relay its functionality to other
    /// objects by invoking delegates. The
    /// default return value for the CanExecute
    /// method is 'true'.
    /// </summary>
    public class DelegateCommand :
        ICommand
    {
        #region Constructors

        /// <summary>
        /// Creates a new command that can always execute.
        /// </summary>
        /// <param name="execute">The execution logic.</param>
        public DelegateCommand(Action<object> execute)
            : this(execute, null)
        {
            Contract.Requires(execute != null);
        }

        /// <summary>
        /// Creates a new command.
        /// </summary>
        /// <param name="execute">The execution logic.</param>
        /// <param name="canExecute">The execution status logic.</param>
        public DelegateCommand(
            Action<object> execute,
            Predicate<object> canExecute)
        {
            if (execute == null)
            {
                throw new ArgumentNullException("execute");
            }
            Contract.EndContractBlock();
            this.execute = execute;
            this.canExecute = canExecute;
        }

        #endregion // Constructors

        #region Private Declarations

        private readonly Action<object> execute;

        private readonly Predicate<object> canExecute;

        #endregion

        #region ICommand Members

        [DebuggerStepThrough]
        public bool CanExecute(object parameter)
        {
            return this.canExecute == null ? true : this.canExecute(parameter);
        }

        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        public void Execute(object parameter)
        {
            this.execute(parameter);
        }

        #endregion // ICommand Members
    }
}
